Bitcoin Under Denial of Service Attack

It’s been a crazy week for Bitcoin, with the crisis in Greece drawing large amounts of attention to Bitcoin. The event has brought a lot of positive coverage on Bitcoin, and also sparked interest in the cryptocurrency from citizens worldwide. However, Bitcoin related events haven’t been 100% positive. For over a day now, an unknown entity has been attacking the blockchain through an automated Denial of Service (DoS) Attack.

What this unknown attacker is doing is spamming the blockchain with dozens of transactions a minute. The perpetrator is sending miniscule amounts of Bitcoin (.00001 BTC) to 34 simple brainwallets, such as cat and dog. The entire transaction costs the sender just 8 cents worth of Bitcoin, and although the transactions are constantly being sent, the attack has been sustained for over a day now with just several Bitcoins to start with.

Because so many transactions are being sent, the attacker is able to single-handedly fill each 1 MB block that enters the blockchain. As this attack is so viable due to a low block size, some speculators believe the goal of this attack is to push a block size increase. Regardless of the intent, the ease at which the attack was conducted certainly does provide evidence to support a block size increase.

Although the attack has certainly been able to fill each and every block for over a day, the actual effectiveness in locking out Bitcoin users is questionable. As many users have stated, by simply increasing the transaction fee that is paid to miners by a small amount, it can be ensure that all legitimate transactions are confirmed in a timely manner.

Another interesting aspect to this attack is it is not necessarily feasible in many other altcoins. By simply requiring a transaction fee to each individual output, which many altcoins already do, this attack can be avoided completely.